<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        let sum = 0;
        for(let i = 1; i <= 100; i++){
          sum = sum + i;
        //   或sum += i;
        }
        alert("1-100的累加和为：" + sum);
    </script>
</body>
</html>